Attitude gyroscope



p 1950 c. E. BARKALOW ETAL 2,523,270

ATTITUDE- GYROSCOPE Filed June 16. 1944 2 Sheets-Sheet 2 24 INVENTORS CLARE E. BAR/(410w 1 ROBERT #45 "vs, (/I?.

Patented Sept. 26, 1950 ATTITUDE GYROSCOPE Clare E. Barkalow, Floral Park, N. Y., and Robert Haskins, Jr., Rutherfordton, N. 0., assignors to The Sperry Corporation, a corporation of Delaware Application June 16, 1944, Serial No. 540,650

6 Claims. (Cl. 74-51) The present invention relates generally to gyroscopic instruments for use on aircraft, and has reference more particularly to an attitude type of gyro instrument wherein an indication of the crafts attitude or position in pitch and roll is continuously provided. The present invention has reference also to a locking mechanism for such instruments. Such an instrument is particularly adapted for use on craft such as military planes which perform intricate maneuvers.

In the drawings and following description of our invention, we have illustrated and described a preferred embodiment thereof as comprising an attitude gyro; but, in its broader aspects, our invention may comprise any type of gyro which is subject to gimbal looking upon deenergization thereof. In furtherance of a more complete understanding of the following discussion relative to the torques causing gimbal lock to occur, it may be here briefly pointed out that an attitude gyro comprises a rotor bearing case within which the gyro rotor spins normally about a vertical axis. The rotor bearing case is rotatably supported on trunnions in a gimbal ring which in normal operation of the instrument lies in horizontalplanes and which, in turn, is supported in the case of the instrument to pivot about an axis preferably aligned or parallel with the fore and aft axis of the craft on which the instrument is mounted. It will be understood, of course, that our invention is applicable to a gyroscopic instrument whose gimbal axis may be aligned with other axes of the craft, such as, for example, the athwartship axis. However, in the following description we will refer to the former casewherein the gimbal pivotal axis is aligned with the fore "and aft axis of the craft.

With instruments of this type, it has been found that under conditions that very often exist when the power is turned off, the gyro rotor bearing case will precess into a gimbal lock position, that is, into a position wherein the rotor spin axis parallels the gimbal pivot axis. The rotor case is caused to precess into a gimbal lock position by a torque produced by the decelerating rotor. For example, when the pivotal axis of support of the gimbal ring does not lie perpendicular to the spin axis of the gyro rotor and the gyro spinning-power is cut off, the torque produced by the decelerating rotor may be resolved into components, one of which occurs about the axis of the gimbal ring, thereby causing the rotor case to precess toward gimbal lock position.

Let the torque'produced by the deceleration of the rotor be represented by a vector T which lies along the spin axis of the gyro rotor. When the spin axis is perpendicular to the fore and aft axis of the gimbal, the torque vector T is also perpendicular to the gimbal axis, and there will be no component of torque about saidgimbal axis. ,However, if the fore and aft gimbal axis is not perpendicular to the spin axis, the torque vector will be inclined at an acute angle with respect to the fore and aft axis, and may now be resolved into two components, component TX, lying in a horizontal plane and component Ty, lying'in a vertical plane.

The TX component lies in a direction parallel to thefore and aft axis of the gimbal and the Ty component in a direction perpendicular thereto. The component Ty is annulled by the reaction forces set up in the bearings in which the trunnion of the gimbal ring is journaled, but the TX component is an effective torque about the fore and aft gimbal axis, causing precession of the rotor bearing case toward gimbal lock. Since the gimbal-ring also precesses or rotates under this effective torque, it may assume a vertical position with the spin axis of the gyro rotor and the gimbal axis aligned, when a gimbal lock condition obtains. The value of the TX component may be expressed as Tas= T cos .a

where a. is the acute angle between the spin axis and the fore and aft axis of the gimbal and T the total torque along the spin axis of the rotor. As, an example, suppose this instrument be mounted in an airplane and it is coming in for a landing. The pilot busies himself with getting his ship on the ground, turning off the power to his instruments after he has landed. When the ship comes to rest, it assumes a position, for most types of craft, wherein the planes fore and aft axis is at an angle to the horizontal. Usually this angle lies in the range of from 10 to 20, and .therefore the gimbal axis of the attitude gyro will also lie at this angle to the horizontal. When the instrument is turned off, the spin axis of the rotor will be in a vertical position but will lie at an angle to the fore and aft gimbal axis.

The torques producedby the decelerating gyro rotor will precess the gimbal ring into a vertical position and the rotor bearing case into a position' Where the spin axis is aligned with the gimbal axis. If the'instrument is startedagain while the rotor is still spinning its bearing case will nutate violently and assume any position such as upside down or lying on its side and any erection system which is employed will take a long time in processing it to its normal vertical position.

In order to prevent the precession of the gimbal ring and rotor bearing case into a gimbal lock position upon deenergization of the instru-' ment, we. propose.- to maintain; the gimbal rin in its normal horizontal plane relative to the'hori zontal plane of the craft and thereby eifectively cancel the torque component TX explained above.

It is, therefore, an object of the present. inuvenr ment about its axis of support when the instru-' ment is shut off to effectively prevent the instrument from going into a gimbal lock position.

Stil another object of the invention resides in providing means adapted to frietionally engage the gimbal ring of a gyroscopic instrument, thereby preventingprecessioninto gimbal lock, when the instrument is deenergizedi A further object of the invention is to provide in a gyroscopic instrument, electrically controlled means which, when deenergized', will resist pivota1 movement of the gimbal ring and thereby prevent the instrument fromassuming a g-imbal lock position.

With these and other ob i'ects and advantages: in; View, the invention includes the novel correlation and combination of elementsd'escribed in the following detailed description of the same and illustrated in the accompanying drawings,

wherein: m

Fig. l'is a longitudinal elevationalview shown partly in section of a gyroscopio instrument on which the invention may effectively be employed. Fig. 2 is a plan elevational View of a part of theinstrument shown in Fig. 1-, showing the rela tiveposition of the elements of our-invention.

Fig. 3 is a partial end view of the instrument with its outer cover removed. j

"Fig. 4 is an electrical wiringdiagram of the instrument showing the correlation of the electrical parts.

Fig. 5 is a View similar to a portion of Fig. 1, showing a modification of our invention.

Fig. 6 isawiring diagram similar to Fig; 4', but applied to the modification shown in Fig. 5f

Figs. 7 and 8' are schematic. representations showing another modification of the present invention.

As stated above, our invention is particularly adapted for use on an aircraftgyroscopic instru ment which will give an indication of the attitude of the craft throughout: 3.6.0? of movement.v That is, during: any maneuver thelcrai t might: go through, the pilot will' get a. true indication of: his attitude in space. Such an instrumentv together with its erecting means is described: in the copending. application ofrEsvai, Wrigley and Haskins, SerialNo. 44.5.7610; dated. June 4, 1942- for Attitude Gyros. now abandoned;v and. in; our copending application. Serial No. 496,930,. filed July .1, 1-943, nQw'Batent;kIo.. 2. 923995.

Referring nowtQ -th-Q drawings;v a yroscope; ofthis form is: shown in. Figure: 1. Theinstrm. ment. comprises generally a casing to adapted for in tallationin the instrument anel ofan aircraft. ThQuGiiSiIlQ H): has. awindow ljl, in-th-e;

f i. thereczfnWhicndisoIQses. he .mdicatinggelee suitable bearings 11.

' trunnion axis l5.

ments of the instrument. The entire casing is enclosed with a thin metal cover 12 to protect the delicate parts of the instrument from dust, moisture, etc. The casing I 0 is provided at its rearward end with a rearwardly projecting hub l3 adapted to pivotally mount the gimbal ring M along theidriitudinal axis I5 of the instrument. The gimbal ring H! is generally U-shaped and is provided with an elongated trunnion l6 which is supported at its one end in hub I3 by The forward support of the gimbal trunnion 16 consists of two forwardly extending bracletsflll and I9 on the casing III which supportsfai suitable bearing member not shown. A rotor bearing case 2| provided with suitable trunnions 2!. is pivotally mounted betweenv the arms. ofthe U-shaped gimbal M for movement about a horizontal axis 22 normal to A gyro rotor 23 is mounted in rotor bearing case 2| to spin about a vertical axis 24 normal to both "axes l5 and 22. Rotor bearing case-2 has mounted thereon a circular shell 25 whichhas onthe surface there-of suitable V markings 26 whicl'i when viewed through window I I will give the pilot an indication of the attitude of his craft. Thesemarkings are read in connection with a fixed horizon bar 21 and vertically adjustable reference 28'; the same being adjusted whose stator windings are shown schematica-l ly in the wiring diagram'of Fig. 4; The elec-:

trical energy is supplied to the rotor through axis 22 as by hair pin member 31' and leai' spring mem-' ber 32' and through axis t5 by sll-p ring members 33. Electrical? energy is supplied through a plug 3'4 suitably-- mounted casing I l] and through suitable leads to thevarious electrical parts of the instrument;

Erection of gyrosc'opic instruments of'this charactor is accomplishedby electromagnetic means. As shown in Fig; I, an e-lectromagnet 35 is universally supported in'casing H! in suchv a manne'r as to-maintain a position directly under a substantially cup-shaped inductor member 36; fixedly'mountedfito theigyro rotor 23? and rotatable therewith. The universal mounting for saidmagnet. 'rnem'ber consists of a yoke 31- rotatably mounted on said'casing by bearings 3.8 for pivotal movement about axis l5;, andia bail: 310 rotatably mounted on the free. ends: of said yoke 31' for pivotal movement about. axis 22... The erection torques are. produced by the interactionof' themagnetic field-produced'by magnet 3.5 and the re,

under'the inductor member; 316;, and during certain' maneuvers oi the? craft; it is desirable.v to. render i the magnet; unernergized, as described, in de.- tail in the above mentionedapplication. As disclosed therein, whentheicrait has-reached oneof the limiting: positions of the erection. system, a switch 39; (see- Eig; 41). is openedrthus. breaking the energizing circuits of the electromagnet. 35: of;-

the erection device.

The, mechanism for resisting; thelpivotal move- 1 members: 38' at axis ment of the gimbal ring about its axis of supp l5 comprises generally, an electrically controlled brake shoe member resiliently mounted on the casing of the instrument which cooperates with a drum member fixed to the gimbal of the gyro. Described in more detail with reference to'Figs. 1-3, this mechanism comprises a brake'shoe 4| which is suitably fastened to one arm of a U- shaped spring 42 as by rivets or the like. The other arm of spring 42 is in turn securely'fastened to the hub l3 of the instrument casing l0. U-shaped spring 42 is so constructed as to exert a tensional force between the arms thereof instead of a compressional force when it is relaxed; that is, the arms tend to draw together instead of push apart. A cooperating drum 43 is securely fastened to the end of elongated trunnion l6 of the gyro gimbal i l by means of the bolt and nut arrangement indicated at 44 so that the drum 43 turns with the gimbal Hi. The configuration of and 3. As there shown, the drum 43 comprisesa substantially rectangular piece of metal or other relatively stiff material which is attached to the gimbal trunnion H5 at its center. The edges of the long side of the rectangular brake member are shown as being flanged toward the rea'r'of the instrument as shown at 45 for purposes that will become apparent as the description proceeds. It will be understood, of course, that the brake drum may assume any convenient shape such as circular and is not necessarily limited to a rectangular configuration.

The control means for the brake shoe 4| comprises an electromagnet 45 which is mounted to instrument casing 15 and'receives its electrical energy from the same source of direct current as the erecting magnet 35. The shoe member 4| is, in effect, an armature of the magnet 46. The two magnets 35 and 46 are electrically connected in parallel (see Fig. 4:) rather than in series because when the craft assumes positions beyond the limits of the erection system magnet 35 is deenergized by action of switch 39 and at this time deenergization of the magnet 46 would obviously be undesirable.

In operation, assume the instrument to be on, and the craft on the ground just after making a landing. Assume also that the fore and aft axis of the craft is not level (actually it wont be in a majority of cases). In this case, the gyro rotor casing 2| will maintain its vertical position, but the gimbal will be in line with the inclined fore and aft axis of the craft. Now, the

instrument is turned off by throwing switch 41 'the drum 43 may more clearly be seen in Figs. 2

action of spring 42 and frictionally engages the drum 43, thus preventing gimbal M from pivoting about its fore and aft axis l5. By prevent ing pivotal movement of the gimbal about this axis, the rotor casing 2| cannot precess into a gimbal lock position, a explained above. A schematic representation of a gyroscope of this character is shown in a gimbal lock position in Fig. '7.

If, for some reason, the instrument is turned off during flight and the craft was, for example, in a bank position, the brake shoe 4| will not engage the drum 13. However, at some time during deceleration of the rotor, the plane will become horizontal and the shoe 4| will ride up on the flanged edge 45 and thus restrain the M from further movement.

In Fig. 5'there is shown a modification of the invention, -In this case, magnet 46 is replaced by a resistance coil 48 which is wound around a hollow core member 48 and is in turn mounted on an extension 49 on the casing ll! of the instrument. The brake shoe in this modification is a bimetallic element 55 adapted to freely fit gimbal through hollow core 48' and has one end securely fastened to the extension 49 as indicated at 52. To the free end of the bimetallic strip is secured a shoe piece 53 which cooperates with drum 43. When the current to the instrument is on, current to the coil 48 is also supplied and the bimetallic strip 5| is heated thereby bending it away from drum 43; however, when the current is turned off by throwin switch 4! (see Fig. 6) the bimetallic strip cools off and it straightens out allowing the shoe piece 53 to contact and frictionally engage drum 43.

A further modification is shown in Figs. 7 and 8, wherein the gimbal I4 is restrained from pivoting aboutaxis i 5 during deceleration of the rotor by making the gimbal slightly pendulous. To this end, then, there is disposed on opposite sides of the gimbal i4, two hollow cylinders 55 and 55, each with their long axis perpendicular to the gimbal axis l5." Each cylinder contains a ball 54 which is free to move therein from one end to the other. If the gimbal assumes the position shown at the end of thedeceleration period, both balls will lie to one side or the other of the central position shown, thereby providing a torque due to unbalance and causing the gimbal to rotate about axis l5 until it is again horizontal. The position of ball 54 in Fig. '7 is one of unstable equilibrium and cannot be attained under normal operation. The gimbal will then always lie in the horizontal position when the rotor is started and will perform in a normal manner. The importance of this feature will be realized if it is remembered that in this type of universallymounted gyroscope having no limit stops, the gimbal ring may assume a position with either side i 4 or M uppermost, due to gimbal look as explained in the aforesaid application of Esval, Wrigley and Haskins. If the gimbal ring were made pendulous inthe ordinary manner in one position, it would be antipendulous with the other side up. With our invention, however, the balls 54 render the gimbal pendulous when the minor axis 22 is horizontal, no matter which side M or it is up, by always displacin the center of gravity to the low side.

Since many changes could be made in'the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In asyroscopic instrument of the character described, an instrument casing, a gimbal ring. rotatably supported in said casing to pivot about a first axis, a rotor bearing case having a gyro rotor mounted to spin therewithin and supported on said gimbal ring to pivot about a second axis, brake means for maintainin said gimbal in fixed relation to said instrument casing comprising a drum member fixedly mounted con :sai'd gimbal, ianaasso'ciated bimetallic ieshoe iadescnibedmn instrument sea-sing, 1 3,3: gimbal z'ring rrmemberzrfixedntossaidgcasingg:electrical-means. for rrotatably supported-in-i-said"casing to pivot ab'out controlling the position-.of said-lbimetallicrashoe 's'aafirst?axis,-:a.-rotorshearing .case supported ion smemberp -andl manually operable-meansioriconsaidsgimbalsring to :pivot-about a second axis, strolling theienerg-iza-tionof. saidelectrical:means. i-el ectricalimeans for erecting said :rotor --.case, -..-2.'=:In a; gyroscopicinstrument ofithemharacter :braki-ngsmeansiincludingeadrum fixedlymounted udescribed an instrument casing,-a=-;.gimbal ring iomsaidrgimbal ringa-nda brake shoe capable of .irotatably supported in said casingqtorpivotsabout -l engagingrsaid drum mounted3onsaid casing-elecmaa-first :axis, a-.==rotorbearing casea-having i-af gyro 115110311 means POperable-to normallyvdisengagesaid izrotonsmountedstorspin therewithirnandsupportedm -shoeSand .drum, and-means for simultaneously on said gimbal. ring- .to pivot .abouteansecond axis, rendering .-.said --.-e1ectrical erecting -means and electrical.- means forespinning said rotor, .wbrake electrical disengaging meansineffective. .imeans :forsmaintainingcsaidsgimbal vin fixed .ree6. rIma: gyroscopicinstrumenti of: thetcharacter elationto said instr'umentcasing comprising .;a -':'described,i-ani instrument-casing;asgimbal ring wdrummember fiXedIy. mounted onv-said-i gimbal, 4 z-rotatably supported in saidica'sing to pivot about -xan associated bimetallic. shoe .memberl-fixedl to ian fiist axisgzalrotor bearing case having:a* gyro saidcasing,ae1ectrical.meansifor-controllingvthe zrotornmountedthereine supported on: said gimbal upositionof said bimetallic-shoe.member,s:and;a iringvto pivotrabout a-secondaxis;electrical-means common switch "for energizing said spinning Zion-spinning :said 'rotor, electrical means "for mneans iandisaid electricalmeans. I i- -ie1fectiiig-saidrotorcasejbraking means-including '3. Invargyroscopicl instrument oftheflcharacter saedrum rfixedlyimountedon said-gimba1-ringand described, an instrument Leasing; aigimbahring e-a'ebrake -shoe capable of engaging said Edrum irotatablyr supported insaid. casingtopivotabout vmountede on said:casingyelectrical means operlla'jirstaxis a rotoizbearingicase supported in said -ableito-l normally disengagesaid shoe and-idrum, sgimbatringto. ivotcaboutz alsecondsaxis, .elecvandimeans for :simultaneously -rrenderingi-said .ltric'al means. forrerectingsaid rotor.-case,.ibraking -=-electr-ica1 erecting :means, said -.electrical ?rotor .Jneans includingia drumifixedly mountedon said s spinningnmeans rand said-v electrical disengaging agimbalringand a brake shoe engaging with. said im'eans-ineffective.

.d-rum -mounted on said u casing, electrical -..-means CLARE BAR-KALOW. .ufor disengag ng said shoe. and' drum andmeans ROBE-RT HA-SKINS, JR. Qfonsimultaneously renderingesaid electrical .erectr ingmeans andielectrical brakedisengagingnneans I ES CIT -efiectlve- The following references are 'of'irecoldf'infthe 4."In aL gyroscopiclinstrument-of.th character ,u r this matent; described, .an;instrument ca'sing as'gimb'aLring .rot'atably supported'in said casing to,.pivotmabout UNITED STATES PATENTS .'.a first axispa rotor-bearing case'. haVing-la'.'gyro ::Number Name Date srotor mounted thereinsupported in said .gimb'al i'Re.-=20,-701 aGillmor '-Apr.-19;11938 .ringtopivot about a second. axis, elect'ricalmeans --:l:;586.,525 .J-Ienry June11,v1926 :Ifor spinning lsaidlrotor, electrical means-.for x40 e1-;988-,463 :Schenk Jan. .22, 1935 erecting-said rotor case, brakingmeans including :2,175;6-31 :Koster 'Oct.:10,-'1939 adrum'ifixe'dly mounted on sai'dgimbalring and 2=, 232,537 rKollsman Feb. 18,1941 va" brake shoe engaging with said drum mounted 42,289,520 -Br-andt May 1-9, 1942 on said casing,electrical. meanseforidisengaging 3:2;393 413 =Jones --Jan.-22,-1946 said shoe and drum, and switch means. settable 22 428545 Turnerjs '-S'ept.-30-;:1947 to permit simultaneous energization of said-selectrical' erecting means,';said..electrica1 rotortspin- FOREIGN PATENTS "ningimeans and said electricalbrake;disengaging 'rNumbeI Gollntry Da 'meang 511,742 Greatl-Bnitain Aug-23,1939

Iniai'gyroscopic instrument" of thegehanacter 95,595 sSweden Mara, 1939 

